New synthetic procedures have been developed for potentially useful metallacalixarene building blocks. The metal sites were covalently connected to calix[n]arenes (n = 4, 6) by oxidative addition of 4-iodobenzyl precursors to either Pd(PPh3)4 or Pd2(dba)3/tmeda (dba = dibenzylideneacetone) to furnish calixarene-modified aryl-Pd(II)I(Ln) complexes [Ln = bis-PPh3 or N,N,N’,N’-tetramethylethylenediamine (tmeda)]. Methods were explored for the selective preparation of mono-Pd(II)-calix[4]arene and di-Pd(II)-calix[n]arenes (n = 4 or 6) complexes and also for bifunctional calix[4]arene synthons with two Pd(II) complexes accompanied by 4-pyridylmethyl or 4-cyanobenzyl groups. The properties of the Pd(II)-calix[n]arenes were studied in detail by one- and two-dimensional NMR and mass spectrometric techniques. The X-ray molecular structures of two 4-iodobenzylcalix[4]arene precursors were also determined.
![Multinuclear calixarene synthons with covalently linked aryl-palladium(II) complexes](https://www.iciq.org/wp-content/uploads/2014/03/Multinuclear-calixarene-synthons-with-covalently-linked-aryl-palladiumII-complexes_eng_noticies_articles_2004_10.gif)